DIN 50 900, T1, April 1982 gives this definition: "Locally accelerated corrosion in gaps. It is due to corrosion cells caused by differences of concentration in the corrosion medium." Gap corrosion on mechanical seals is found mostly on the atmosphere side close to the secondary seals and beneath deposits; it occurs less often in or on parts immersed in the process medium.

Deposits in narrow gaps and the startings of corrosion on the inner diameter of the sliding face